Liang Hao, Otsubo Kazuya, Otake Ken-Ichi, Kitagawa Susumu, Kawaguchi Shogo, Yamamoto Tomokazu, Murakami Yasukazu, Kitagawa Hiroshi
Division of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto 606-8502, Japan.
Institute for Integrated Cell-Material Science (iCeMS), Kyoto University, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan.
J Am Chem Soc. 2023 May 3;145(17):9454-9458. doi: 10.1021/jacs.3c02252. Epub 2023 Apr 24.
The use of nanotubes in the solution state is crucial not only for the exploration of physical and chemical behaviors at the molecular level but also for application such as thin-film fabrication. Surface modification is generally used to solubilize carbon nanotubes (CNTs) and various synthetic nanotubes; however, this method may affect the surface properties of the original nanotubes, and the detailed crystal structure obtained after modification is unclear. Here, we report the synthesis of a crystalline and soluble metal-organic nanotube consisting of a cationic tubular framework and an anion with a long alkyl chain. The nanotubular structures are formed not only in the solid state but also in the solution state, as confirmed by an X-ray structural analysis, optical measurements, and electron microscopy studies. This nanotube system is realized in different states without any surface modification, which is quite different from typical CNTs and synthetic nanotubes. In addition, self-assembled crystalline bundles are directly observed using transmission electron microscopy (TEM) for the first time in a metal-organic nanotube system. The bundle structures are also confirmed by atomic force microscopy (AFM) observations of thin nanotube films. We envisage a systematic design of such soluble metal-organic nanotubes that will enable direct observation of mass transport behavior in channels of bundles or a single nanotube, as well as a wide range of thin-film applications.
溶液态纳米管的应用不仅对于在分子水平探索物理和化学行为至关重要，而且对于诸如薄膜制造等应用也很关键。表面改性通常用于使碳纳米管（CNT）和各种合成纳米管溶解；然而，这种方法可能会影响原始纳米管的表面性质，并且改性后获得的详细晶体结构尚不清楚。在此，我们报告了一种由阳离子管状骨架和具有长烷基链的阴离子组成的结晶且可溶的金属有机纳米管的合成。通过X射线结构分析、光学测量和电子显微镜研究证实，纳米管结构不仅在固态中形成，而且在溶液态中也形成。这种纳米管体系无需任何表面改性即可在不同状态下实现，这与典型的碳纳米管和合成纳米管有很大不同。此外，首次在金属有机纳米管体系中使用透射电子显微镜（TEM）直接观察到自组装结晶束。通过对纳米管薄膜的原子力显微镜（AFM）观察也证实了束状结构。我们设想对这种可溶金属有机纳米管进行系统设计，这将能够直接观察束状或单个纳米管通道中的质量传输行为，以及广泛的薄膜应用。
